Tertullian of Carthage (ca. 155- after 220 CE), who introduced the term “Trinity” from the Latin “trinitas” (three or triad), taught the concept of one God in three persons: the Father, the Son, and the Holy Spirit. These three are distinct, but not separate. Because these three persons are not separate or divided, God is one, not three. Tertullian’s Trinity is, therefore, a form of monotheism not tritheism.
Another form of the Trinity, which Tertullian considered heresy, is known as “Sabellianism,” after the 3rd century theologian Sabellius. “Modalism,” as it is also known, states that God is one in three aspects or modes. In this version, the Father, the Son, and the Holy Spirit are not distinct persons but different manifestations of the Godhead. Accordingly, it was God who suffered on the cross, hence this view is also called “patripassionism,” which is derived from the Latin words for “father” and “suffer.” Like Tertullian’s version, this form of the Trinity equally claims to promote the oneness of God.
In the 4th century a major controversy broke out between Bishop Alexander of Alexandria, Egypt, and the Alexandrian priest and theologian Arius. The former believed that the Father and the Son were both eternal and of equal status. Arius believed the Son was not eternal and was inferior to the father. The Arians, while still advocating the divinity of the Son, insisted that there is substantial difference between the Father and the Son.
The spread of this controversy prompted Emperor Constantine to arrange and oversee the first Ecumenical Council, which was held in Nicea in 325 CE. The convening bishops, whose number has been put by different sources between 250 and 318, released the first decree that addressed the status of the Father and the Son and their relationship, but it only affirmed the belief in the Holy Spirit. This decree was not the result of as much consensus as Constantine’s influence and pressure. Having been given the choice of signing to the decree or being sent into exile, Arius and his allies chose the latter. The wording of the decree was vague and open to different interpretations, but it was still clear enough to reject Arianism:
We believe in one God, the Father, almighty,
maker of all things visible and invisible;
And in one Lord Jesus Christ, the Son of God,
begotten from the Father, only-begotten, that is,
from the substance of the Father, God from God,
light from light, true God from true God,
begotten not made, of one substance with the Father,
through whom all things came into being,
things in heaven and things on earth,
Who because of us men and because of our salvation
came down and became incarnate, becoming man,
suffered and rose again on the third day, ascended to the heavens,
will come to judge the living and the dead;
And in the Holy Spirit.
But as for those who say, there was when He was not,
and, before being born He was not,
and that He came into existence out of nothing,
or who assert that the Son of God is of a different
hypostasis or substance, or is subject to alteration or
change — these the Catholic and apostolic Church anathematises. (Kelly, 1999: 215-216)
In the following half a century the debates and disagreements continued unabated, and when the second Ecumenical Council was convened in Constantinople in 381, the convening 150 bishops revised the creed and gave it its final shape, which now addressed the status of the Holy Spirit also and, thus, the doctrine of the Trinity:
We believe in one God, the Father, almighty,
maker of heaven and earth, of all things visible and invisible;
And in one Lord Jesus Christ, the only-begotten Son of God,
begotten from the Father before all ages, light from light,
true God from true God, begotten not made,
of one substance with the Father, through whom all things came into existence,
Who because of us men and because of our salvation came down from heaven,
and was incarnate from the Holy Spirit and the Virgin Mary and became man,
and was crucified for us under Pontius Pilate,
and suffered and was buried, and rose again on the third day
according to the Scriptures and ascended to heaven,
and sits on the right hand of the Father,
and will come again with glory to judge living and dead,
of whose kingdom there will be no end;
And in the Holy Spirit, the Lord and life-giver,
who proceeds from the Father, who with the Father and the Son is together
worshipped and together glorified, who spoke through the prophets;
in one holy Catholic and apostolic Church.
We confess one baptism to the remission of sins; we look forward to the resurrection of the dead and the life of the world to come. Amen. (Kelly, 1999: 297-298)
The deletions from the Nicean formulary and the additions, which I have highlighted in bold above, are instructive in understanding issues that were at the centre of the debates between Christian theologians.
Some doubts have been raised about whether this revision was made in the 381 council (Kelly, 1999: 305-331). It is first mentioned as an official formulary in the Chalcedon Council in 451 CE where the convening bishops clearly believed that the creed had been composed and ratified in Constantinople.
The Niceno-Constantinopolitan Creed, as it has become known, was accepted by both the Eastern and Western Churches. The history leading to the formulation of this authoritative formulary, however, was full of controversy, and the consensus that was finally achieved conceals many bitter battles and much struggle between prominent churchmen who held opposing views. For a detailed study of the history of the development of this creed, the reader may like to see Early Christian Creeds (Kelly, 1999).
The development of the Trinity was simply a consequence of the introduction of the more fundamental doctrine of the Incarnation. This is how one prominent scholar explains it:
The doctrine of the Trinity was developed as an interpretive framework to secure the prior doctrine of the deity of Christ. That is to say, if Jesus Christ was God incarnate, but if throughout the period of his earthly life God was also at work sustaining the universe, receiving prayer and otherwise acting outside the person of the historical Jesus, it follows that the Godhead is as least two-fold, namely Father and Son. This was the essential expansion or complication of monotheism required by the belief in divine incarnation. And when the Spirit of God, attested to in religious experience is added, we have a Trinity. (Hick, 1997: 7)
Jesus was not the only holy figure that Christianity deified. His mother Mary was also later transformed into an object of worship in a doctrine known as Mariolatry or the “worship of Mary,” even though there is nothing to support this exaltation of Mary’s status in the New Testament. Among the titles Christians conferred on Mary are “Mother of God” and “Queen of Heaven.” Mariolatry led to the introduction of dogmas such as the “immaculate conception,” by Pope Pius IX in 1854, which states that Mary was free of the original sin from birth, like Jesus. Another dogma is the “assumption of Mary,” by Pope Pius XII in 1950, which teaches that after her death, Mary’s soul and body were taken to heaven.